Deposition and characterization of HfO₂ high k dielectric films

As the scaling of complementary metal-oxide-semiconductor (CMOS) transistors proceeds, the thickness of the SiO₂ gate dielectrics shrinks rapidly and results in higher gate leakage currents. High k dielectric materials are acknowledged to be the possible solutions to this challenge, as their higher k values (e.g., 15–50) raise the physical thickness of the dielectrics that provide similar equivalent thickness of a thinner SiO₂ film. In order for the high k materials to be applicable in CMOS devices, there should exist deposition technologies that can deposit highly uniform films over Si wafers with diameters as large as 200 mm. This report discusses the deposition process and the correlation between the growth conditions, structural and dielectric properties of HfO₂, which is one of the most promising high k dielectric materials. Judging from the thickness uniformity, surface roughness, k value, and interfacial density of state of the HfO₂ films, the metalorganic chemical vapor deposition technique was identified to be suitable for growing HfO₂ films targeted at applications as CMOS gate dielectrics.